Transferring or migrating Flickr photos to SMugMug is done through third party softwares. There are many apps & tools that you can use to transfer photos between online photo sharing services. The easiest tool available is PicBackMan. Its fast, it is easy and it automates the upload process.
Moving photos from SmugMug to Flickr was never this easy. All you need is PicBackMan. Install, connect your SmugMug and Flickr accounts and PicBackMan does the rest. All your photos will be migrated from SmugMug to Flickr almost automatically. Try it if you haven't yet.
You can now install PicBackMan's SmugMug uploader for Mac from the website to backup upload and download SmugMug Photos effortlessly.